342 EXPLANATION OF THE PLATES. 



will be forced through into the air vessel E, and the supply for the descending 

 stroke will rush in by the bottom valve from F, and, as before, be discharged 

 through G. 



For the proportions of this kind of engine (see art. 414 423). I would re- 

 commend the adoption of Field's valve instead of the throttle valve. See 

 art. 547. 



PLATE XIV. 



This plate represents a double acting steam engine, for impelling machinery, as 

 executed by Messrs. Fenton, Murray, and Co., of Leeds. 



The engine is supported by the walls A A A A, part of which form the walls of the 

 engine house. The steam cylinder B is secured to the wall below it by bolts ; it is 

 enclosed in a jacket or casing of cast iron, a little larger than the cylinder, and the 

 space between them is supplied with steam, to keep the temperature of the cylinder 

 as near to the temperature of the steam as possible. (See art. 155.) The steam 

 comes from the boiler by the steam pipe C C, to the valve pipe D D, and passes 

 to the condenser by the eduction pipe E E, leading to the condenser F, which 

 with the air pump G is immersed in the cold water cistern H, supplied through 

 the pipe J. The cold water pump I is worked by the rod O attached to the 

 engine beam. The air pump is worked by the rod N, and delivers the water 

 into the hot well, from whence the hot water pump K, worked by the rod P, the 

 upper part of which is connected with the working beam at Q, raises a quantity of 

 hot water to supply the boiler. 



The working beam Q is supported by the cast iron column R, and is connected 

 to the piston rod L by the parallel motion M M (see art. 188) ; the other end of 

 the beam gives a rotary motion to the crank shaft by means of the connecting rod 

 S, the lower part of which is attached to the crank T ; and a spur wheel U on the 

 crank shaft, working into a pinion on the shaft V, gives motion to it, and to the 

 fly wheel W, (see art. 540.) By means of a train of shafts and beveled wheels 

 X Y Z, moved by the crank shaft, the axis, carrying the eccentric rollers which 

 move the valves, is kept in motion, and the rods a b, which are connected to the 

 valves, are raised and depressed at the proper times, or by hand by the lever e, 

 in the manner more fully described in Plate vui. In some of their engines 

 they use slides nearly of the kind mentioned in art. 447. The injection of cold 



